linux-kernel - [PATCH v4 0/2] hwmon: scmi: Scale values to target desired HWMON units

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Message-Id: <20190508170035.19671-1-f.fainelli@gmail.com>
Date:   Wed,  8 May 2019 10:00:33 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     bcm-kernel-feedback-list@...adcom.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-arm-kernel@...ts.infradead.org,
        linux-hwmon@...r.kernel.org (open list:HARDWARE MONITORING)
Subject: [PATCH v4 0/2] hwmon: scmi: Scale values to target desired HWMON units

Hi Sudeep, Guenter,

This patch series adds support for scaling SCMI sensor values read from
firmware. Sudeep, let me know if you think we should be treating scale
== 0 as a special value to preserve some firmware compatibility (not
that this would be desired).

Changes in v4:
- deal with overflow in the caller of __pow10() as suggested by Guenter
  which makes us rework a bit how the value argument/return value are
  passed
- don't harcode the latest power of 10 factor to be 18, just rely on
  overflowing the u64 value instead

Changes in v3:

- add a local __pow10 function to scmi-hwmon.c while a plan to provide
  a generic function is figured out.
- add check on power > 18 which would overflow a 64-bit unsigned integer
- use div64_u64() to properly divide a 64-bit quantity with an unsigned
  64-bit quantity

Changes in v2:

- added a helper function in kernel.h: __pow10()
- made the scale in scmi_sensor_info an s8 type, added defines for
  checking the sign bit and sign extending with a mask
- simplify computations in hwmon driver

Florian Fainelli (2):
  firmware: arm_scmi: Fetch and store sensor scale
  hwmon: scmi: Scale values to target desired HWMON units

 drivers/firmware/arm_scmi/sensors.c |  6 ++++
 drivers/hwmon/scmi-hwmon.c          | 46 +++++++++++++++++++++++++++++
 include/linux/scmi_protocol.h       |  1 +
 3 files changed, 53 insertions(+)

-- 
2.17.1